The accessory connectors on Uniden LMR radios never came fully loaded. They alwasy left them open for dealers choice. In the case of SMU4525KT there are only 3 pins wired from the factory. Pin 1 is Ground. Pin 2 is the main audio line from the audio amplifier. Pin 3 goes to internal speaker. The radio would come from the factory with a white jumper wire connecting pins 2 and 3 together to activate internal speaker. If you want external speaker you cut the jumper and connect the speaker across pins 1 and 2. All the other pins are open. If you would like a schematic let me know.